HWC2On1Adapter: populateCapabilities: fix virtual display query

To determine whether a HWComposer implementation supports virtual
displays, HWC2On1Adapter::populateCapabilities() calls
query(HWC_DISPLAY_TYPES_SUPPORTED). However, it incorrectly uses
HWC_DISPLAY_VIRTUAL instead of HWC_DISPLAY_VIRTUAL_BIT. Update the
check to use the correct bitmask.

Change-Id: I1ad95d5222a0353816ee65936cf033e5244c80cc